Wednesday, July 8, 2015

Should I Do One More Thing For This Year's Crop?

Often growers ask the question, "What if I had done one more thing to this year's crop - would it have affected yield? In a study conducted by researchers at the University of Illinois during 2009 and 2010, five management factors were assessed for their individual and cumulative contributions to corn yield and yield components in a corn-soybean rotation. Five management factors involving plant population, transgenic insect resistance, fungicide containing strobilurin, P–S–Zn fertility, and N fertility were evaluated. A standard treatment was used that simulated commercial corn production. This standard treatment was compared to other treatments involving each additional input and a high technology treatment where all supplemental treatments were applied.

The high technology treatment yielded 46 bu/A (34 to 56 bu/A) more grain (28%) than the standard treatment, This demonstrates a yield gap between traditional commercial farm practices and the attainable yield using available technologies. All management factors except plant population were necessary for reducing the yield gap. Fungicide and transgenic insect resistance traits provided the greatest yield increases. Averaged over sites and years, if each factor was withheld from the high technology system, yield decreased by decreasing kernel number. Increased plant population reduced the yield gap when all other inputs were applied at the supplemental level. Kernel number was more significant for increasing yield than kernel weight. Thee yield contribution of each technology was greater when applied as part of a full complement of supplemental inputs than when added individually to the standard commercial system.

Implications
Although economics are not considered in this article (only yield response), the fact that a 28% yield gain could be obtained with available technology is intriguing. The other important conclusion by the authors is that the technologies are synergistic - all must be used to realize this gain. Yet, the experimental design (omission plots) is NOT able to identify specific interactions between a subset of the management factors. So this conclusion needs further study. It may be that two or three of the factors provide the major yield increase.